Mobile radio frequency (RF) chip designs (e.g., mobile RF transceivers), including high performance diplexers have migrated to a deep sub-micron process node due to cost and power consumption considerations. The design of such mobile RF transceivers becomes complex at this deep sub-micron process node. The design complexity of these mobile RF transceivers is further complicated by added circuit functions to support communication enhancements, such as carrier aggregation. Further design challenges for mobile RF transceivers include analog/RF performance considerations, such as mismatch, noise and other performance considerations. The design of these mobile RF transceivers includes the use of additional passive devices, for example, to suppress resonance, and/or to perform filtering, bypassing and coupling.
The design of these mobile RF transceivers may include the use of silicon on insulator (SOI) technology. SOI technology replaces conventional silicon substrates with a layered silicon-insulator-silicon substrate to reduce parasitic device capacitance and improve performance. SOI-based devices differ from conventional, silicon-built devices because the silicon junction is above an electrical isolator, typically a buried oxide (BOX) layer. A reduced thickness BOX layer, however, may not sufficiently reduce the parasitic capacitance caused by the proximity of an active device on the silicon layer and a substrate supporting the BOX layer.
Unfortunately, a transistor fabricated using SOI technology generally suffers from the floating body effect, in which the transistor's body forms a capacitor against the insulated substrate. In this arrangement, charge that accumulates on the capacitor causes adverse effects, such as parasitic transistors in the structure and off-state leakage, as well as dependence of the threshold voltage of the transistor on its previous states. The floating body effect is especially acute in analog devices, in which threshold voltage control and body charging control are prevented by the floating body effect. A body contact may be used to prevent the floating body effect. Unfortunately, use of a body contact results in an area penalty.